The Kurdish rebel sits fiddling with his Kalashnikov looking bored when a comrade suddenly breaks into screams of "Allahu akbar" as a series of explosions reverberate from the front line.
"Take it easy, take it easy, he can't hear you," says the Kurd, sitting next to a pile of broken glass on the street, his jeans rolled up to reveal knock-off black plimsolls with the word "PRADA" written on the label.
From where he stands checking the IDs of civilians crossing the front line of the Syrian war in Aleppo, he can see the checkpoint of the Kurdish militia reviled by many of his comrades in the overwhelmingly Sunni Arab, Free Syrian Army (FSA).
But although he and his comrades say they are brothers fighting together to bring down President Bashar al-Assad, at their post in the neighbourhood of Bushtan al-Basha they disagree on what a new Syria would look like.
"We need an Islamic government," says 20-year-old Mutassim, before his Allahu Akbar chants, his beard wispy and a crocheted white prayer cap rammed on top of his head.
But the Kurd, who does not want to give his name, says he joined the rebels to avoid national service in President Bashar al-Assad's army, and not to be a "mujahid" like Mutassim.
Asked whether he wants an Islamic government, he gives an emphatic "No".
"We need a government for everyone," he added. After chatting a bit longer, his commander barks across the street for him to go back to his checkpoint. He doesn't move.
One day earlier, clashes broke out nearby between the FSA and Kurdish militiamen as Muslims celebrated Eid al-Adha, in which one watchdog said 30 people were killed.
The fighting in Ashrafiyeh on Friday was the deadliest such incident between Kurds and the armed opposition of the 19-month uprising against Assad and came one day after the rebels moved into the mixed neighbourhood.
The Kurdish Democratic Union Party (PYD), the Syrian branch of the leftist and secular Kurdistan Workers' Party (PKK) that controls the area and which professes to be neutral, blamed both the regime and the FSA for the violence.
There are deep tensions between the PYD, which has been seen as doing the regime's bidding, and the rebels, seen by the Kurds as being influenced by an Islamist agenda.
But the FSA, which is already overstretched and under armed, can ill afford to take on the Kurds, no matter how much their foot soldiers bray for revenge.
Yussef Aboud, a commander in the Tawhid Brigade of the FSA, said the problem had been resolved after the Kurds sent peace emissaries.
"We don't want this problem again because it will make things very, very difficult," he told AFP at his office well behind the frontline.
He calls the Kurds brothers, but warns that could change in a post-Assad Syria. "Maybe in the future unless the PKK corrects their mistakes, but if they stay the same, after we finish Assad and his army, we will (fight the PKK)."
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Peter Harling, analyst at the International Crisis Group, believes such remarks are largely rhetorical given the prospect of defeating Assad is still far off.
Syria's second city of Aleppo is a melting pot for the country's ethnic, religious and sectarian communities that for decades have lived largely in peace.
The rebels say they represent all Syrians, but there is little sign of Christian, Shiite or Alawite fighters in Aleppo.
Neighbourhoods controlled by the main rebel faction, the FSA, are conservative Sunni areas where no woman is seen on the street without skirts to the ground and her head, if not her face, heavily veiled.
Many have reportedly fled to areas controlled by the regime, where there is less risk of being bombed by warplanes or shelled by heavy mortars.
Opposite the Bustan al-Basha checkpoint, a heavily damaged Armenian Christian old people's home has long since been evacuated and is now in the sights of regime snipers.
In a deserted side street, the words "The God of Allah" have been spraypainted in Arabic on the ground floor of an apartment building that houses an Armenian dentist and an Armenian paediatrician.
In what was a mixed Christian-Sunni street, the only clothes hanging out to dry are that of the rebels, many of whom wear black bandanas inscribed with the words: "There is no God but Allah and Mohammed is his messenger".
When asked what would change in a post-Assad Syria, fighters in Aleppo often say that they want an Islamic government and sharia law.
Abu Mahar, who claims to control 200 fighters, said any communal resentment was the work of regime propagandists, but went on to accuse Christians of not being true Syrians.
"Christians have no connection with the country," he told AFP in a gym turned rebel base elsewhere in the city.
"We all love Syria, but if anything happens in Syria, they'll run away, because the West and the regime tell them that if the rebels take over, they'll kill them."
Harling advises caution, saying that at least for now relations between the rebels and the Christians are holding up.
"It could be much much worse than it is. It's not an all-out confessional civil war. This is not Lebanon yet. It could be, but I think they're very different societies," he told AFP by telephone.
Back at the Bushtan al-Basha checkpoint, 20-year-old Kutayba insists there is no incompatibility between an Islamic government and Syria's rich tapestry of minorities.
"No I don't think they (minorities) will be happy (with an Islamic government), but that's what'll happen. We won't hurt them."